Can't decrypt my AES-128 C#-encrypted byte array in java

[MimiMi]

I'm trying to decrypt a byte array in java that was encrypted in C#. I don't get any error messages, just a result that's completely not what I was hoping for.

I think I am using the same type of algorithm, initialization vector (IV), mode, padding, key etc, but I just don't get the two languages to "understand each other", or, in other words, I must be missing out on something crucial.

I encrypt a byte array in C# and send over the byte initialization vector used for encrypting it as well as the encrypted byte to java. In java I use the received initialization vector to try to decrypt the received encrypted byte array. And I don't get anything near the original plaintext.

I leave out the communication code between the two applications since I don't think that's where the problem is. Though I'm not sure, of course, but let's try this first. (Why I don't think that's the problem? I print out the arrays in my C# code as well as in my java code, once they're received in the java code, and they look exactly the same.)

Here's the encryption code I use so you get the idea of the encryption methods I'm using. I'm trying to achieve AES-128, CBC, no padding in both applications.

NOTE: Of course, in my application I use the IV received from C#, not "tmpiv" as in this example. Also, I use the received encrypted plaintext-buffer from C#... yeah, you get the point. I just wanted to post runnable code..

Any ideas or hints to lead me in the right direction would be extremely appreciated! Cheers!

import java.io.*;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
 
 
public class Main {
 
    public Main() {
    }
 
    public static void main(String[] args) {
        byte[] keyBytes = ("abcdefghijklmnop").getBytes();
         byte[] plaintext = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
                              (byte)0x88, (byte)0x99, (byte)0xaa, (byte)0xbb,
                              (byte)0xcc, (byte)0xdd, (byte)0xee, (byte)0xff };
 
         byte[] tmpIV = {0x43, (byte)0x6d, 0x22, (byte)0x9a, 0x22,
                        (byte)0xf8, (byte)0xcf, (byte)0xfe, 0x15, 0x21,
                        (byte)0x0b, 0x38, 0x01, (byte)0xa7, (byte)0xfc, 0x0e};
 
         System.out.println("Plaintext is:");
         displayBytes(plaintext);
 
         byte[] encrypted = encrypt(plaintext,keyBytes,tmpIV);
         System.out.println("Encrypted plaintext is:");
         displayBytes(encrypted);
 
         byte[] decrypted = decrypt(encrypted,keyBytes,tmpIV);
         System.out.println("Decrypting encrypted plaintext, we get plaintext back:");
         displayBytes(decrypted);
 
 
    }
 
     public static byte[] decrypt(byte[] cipherText, byte[] key, byte [] iv)
    {
      try{    
      Cipher c = Cipher.getInstance("AES/CBC/NoPadding");
      SecretKeySpec sks = new SecretKeySpec(key, "AES");
      IvParameterSpec ips = new IvParameterSpec(iv);
      c.init(Cipher.DECRYPT_MODE, sks, ips);   
      //Re-use of "cipherText"
      cipherText = c.doFinal(cipherText);
      }
      catch(Exception e){ System.out.println("Exception caught:"+e.getMessage());}
      return cipherText;
   }
 
     public static byte[] encrypt(byte[] plainText, byte[] key, byte [] iv)
    {
     try{    
      Cipher c = Cipher.getInstance("AES/CBC/NoPadding");
      SecretKeySpec sks = new SecretKeySpec(key, "AES");
      IvParameterSpec ips = new IvParameterSpec(iv);
      c.init(Cipher.ENCRYPT_MODE, sks, ips);
      //Re-use of "plainText"
      plainText = c.doFinal(plainText);
      }
      catch(Exception e){System.out.println("Exception caught:"+e.getMessage());}
      return plainText;      
   }
 
 
     public static void displayBytes(byte[] bytes) {
        StringBuffer ret = new StringBuffer(bytes.length);
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0x0100 + (bytes[i] & 0x00FF)).substring(1);
            ret.append((hex.length() < 2 ? "0" : " ") + hex);
        }
        System.out.println (ret.toString());
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.IO;
 
namespace forumapp
{
    class Program
    {
        static RijndaelManaged rijndaelCipher;
 
        static void Main(string[] args)
        {
          byte[] plaintext = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF };
          Console.WriteLine ("\nPlaintext is: ");
          DisplayBytes(plaintext);
 
          initCrypt();
 
          byte[] ciphered = Encrypt(plaintext);
          Console.WriteLine("\nEncrypted plaintext is: ");
          DisplayBytes(ciphered);
 
          byte[] deciphered = Decrypt(ciphered);
          Console.WriteLine("\nDecrypting encrypted plaintext, we get plaintext back: ");
          DisplayBytes(deciphered);
 
          Console.WriteLine("\nDone");
          Console.ReadLine();
 
        }
 
        public static void initCrypt()
        {
            byte[] keyBytes = System.Text.UTF8Encoding.UTF8.GetBytes ("abcdefghijklmnop");
 
            rijndaelCipher = new RijndaelManaged();
            PasswordDeriveBytes pdb = new PasswordDeriveBytes(keyBytes, new SHA1CryptoServiceProvider().ComputeHash(keyBytes));
            byte[] key = pdb.GetBytes(32);
            byte[] iv = pdb.GetBytes(16);
            rijndaelCipher.Mode = CipherMode.CBC;
            rijndaelCipher.Padding = PaddingMode.None;
            rijndaelCipher.KeySize = 128;
            rijndaelCipher.BlockSize = 128;
            rijndaelCipher.Key = key;
            rijndaelCipher.IV = iv;
        }
 
        public static byte[] Encrypt(byte[] plainBytes)
        {
            ICryptoTransform transform = rijndaelCipher.CreateEncryptor();
            using (MemoryStream ms = new MemoryStream(plainBytes))
            {
                using (CryptoStream cs = new CryptoStream(ms, transform, CryptoStreamMode.Read))
                {
                    return ReadFully(cs);
                }
            }
        }
 
        public static byte[] Decrypt(byte[] encryptedData)
        {
            ICryptoTransform transform = rijndaelCipher.CreateDecryptor();
            using (MemoryStream ms = new MemoryStream(encryptedData))
            {
                using (CryptoStream cs = new CryptoStream(ms, transform, CryptoStreamMode.Read))
                {
                    return ReadFully(cs);
                }
            }
        }
 
        public static byte[] ReadFully(Stream stream)
        {
            byte[] buffer = new byte[32768];
            using (MemoryStream ms = new MemoryStream())
            {
                while (true)
                {
                    int read = stream.Read(buffer, 0, buffer.Length);
                    if (read <= 0)
                        return ms.ToArray();
                    ms.Write(buffer, 0, read);
                }
            }
        }
 
        static void DisplayBytes(byte[] bytes)
        {
            for (int i = 0; i < bytes.Length; ++i)
            {
                Console.Write(bytes[i].ToString("x2") + " ");
                if (i > 0 && i % 16 == 0) Console.Write("\n");
            }
            Console.WriteLine("");
        }
 
    }
}
 

[MimiMi]

My mistake. (Sorry for being such a 'moron'...)
The key is not the same!!
Of course I shouldn't use rijndaelCipher. Key = key, where key = pdb.GetBytes(32 )
(PasswordDerive Bytes).
It should be "rijndaelCipher .Key = keyBytes.
Then it works like a charm!
"I'm so happy, oh so happy..." cheers

[JosAH]

My mistake. (Sorry for being such a 'moron'...)
The key is not the same!!
Of course I shouldn't use rijndaelCipher. Key = key, where key = pdb.GetBytes(32 )
(PasswordDerive Bytes).
It should be "rijndaelCipher .Key = keyBytes.
Then it works like a charm!
"I'm so happy, oh so happy..." cheers

Good you found it yourself; I've been playing with your code a bit and I was
completely on the wrong track and about to check the Sun Bugbase for this
encryption method ;-)

kind regards,

Jos